Electrolytic process.



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It. HOLLIS; OF CHICAGO, ILLINOIS:-

ELECTROLYTIC PROCESS.

Specification 01!;Let-ters Patent. w.-

Patented March 23, 1909-.

To all whom it may concern:

Be it known that I, HENRY L. HOLLlS, a citizen. of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Im rovement in Electrolytic Processes, of which the following is a full, clear, concise,

- and exact description, reference being had to 'fectly uniform in gage, and consequently after this treatment, the higher portions contain less tin and the hollow parts more tin, it being practically impossible to obtain a coating of uniform thickness. For certain classes of work there uirementsare that the amount of plating tm shall not contain less than 1. grains for each four square inches, and to meet these requirements an excess of tin must be used in the dipping process. These requirements, however, can readily be met and uniformity of plating can very readily" be obtained without usinganexcess of tin, by de ositing the tin by electrolytlc means, and t e main object of my in- .vention is to provide a simple and efiicient method for uniformly tinning sheet iron or other iron without usmg-an excessive amount of tin.

In'accordance with my method, I first obtain a proper electrolyte or plating solution.

The electrolyte I thus obtain is in the form of. a tin salt of 'a fiuorin acid. One method of j obtainingthis 'is as follows: A solution of hydro-fluosilicic acid is first prepared by taki seven parts b volume .of hydrofluosi 'cic acid. and a ding to this ninetythree parts, of water. This solution is then used as an electrolyte in which. tin is immersed. as an anode and any suitable metal,. preferal ilyiron, as a cathode. Upon current flow, between the anode and cathode and through the 'solution,tin is dissolved-at the anode and deposited on the cathode, ,but

the rateof solution will be greater than'the rate of deposition, and as the amountof tin in solutlonlgradually increases, the difi'erence decrease until a point is reached to the rate of deposition;

to be plated are first thoroughly cleaned, if necessary, by the pickling process or any other well-known process, and are then imwith the cathode terminal. The iron cathode used in preparin the plating solution having been removed, 51c entire deposit of tin wi take place on the plates to be.tinned. The amount and time of current flow can be very readily and nicely adjusted in any wellknoWn manner to give the desired quality and quantity of latmg. I also add a small amount of a co loid, preferably gelatin or glue, as I find that the addition of a small amount of such colloid renders the deposited metal much more dense and prevents loose and non-adherent deposition on the iron. In practice 'I dissolve the gelatin or glue in hot Water and add this to the solutlonin the proper proportion of about one Weight of gelatin or glue to one undred parts by weight of the electrolyte.

for the forming of electrolyte are not necessary, as good results "can be i'obtained with quantities of colloid and 'with smaller expressed. Neither is it im .tion has been prepared," andIobtainfjgimd fresh electrolyte. previously e ectroly'ticall or otherwise 2. The process of coating'fsheet iron with tin, which consists in preparin a solution comprising hydro-fluosi icic'aci and water, immersing in said solution an anode of tin at which the rate of.,solution is about equal and the solution is then ready for tin plating. "The 'iion'sheets mersed in the plating solution and connected art by The exact proportions expressed above.

diflerent strengths of acid and different tin, which consists in immersing the sheetsin an electrolyte in the form of solution/0f a tin slat of a fluorin acid, and connectin "the sheets as cathodes with .an electro ytic amounts of tin in solution. I do not, thereforefwant to be limited to the proportions} erative toiuse'i tinas an anode after the e ectrolytic-solu go results by using an insolubleQ-M'rod. this case the quantity of tin in thesolution can be maintained-byaddingi asirequired, T prepared. '1 also. find that can perform zinc plating in the same manner. by simply substituting. zinc for tin throu'gh- 10.0 sire to secure the following claims by Letters -,.Patent: p j

- "1. The process ofcoating' iron sheets with and a suitable cathode, causing current flow throu h the solution from the anode to the catho e whereby tin is liberated from the anode and deposited on the cathode, causing the rate of dissolution of tin from the anode to be greater than thedeposition of tin on the cathode whereby the solution becomes impregnated with tin, then using said solution as an' electrolyte, and immersing therein the iron sheets as cathodes.

3. The process of coating iron sheets with tin, which consists in immersing the sheets as cathodes in an electrolyte consisting of a solution of a tin salt of a fluorin acid and a colloid, and causing current to flow through 15 the solution.

In witness whereof, I hereunto subscribe my name this 12th day of August A. D., 1907.

HENRY L. HOLLIS.

Witnesses:

HARVEY L. HANSON, GEORGE E. HIGHAM. 

